Proposed studies will focus on how the spatial orientation and functions of cell-surface proteins in virus-transformed cells depend on their mechanism of assembly into the membrane bilayer. This will involve 1) In vitro synthesis of a virus-coded membrane protein and insertion into membrane in a physiological manner. 2) Identification and isolation of enzymes required for the synthesis and insertion of membrane, but not soluble, proteins, and 3) Analysis of how the mechanism of assembly controls membrane protein functions. The M13 coat protein, which is a membrane protein during several stages of its infectious cycle, will be used to study these questions. Preliminary investigations have shown that this protein has an asymmetric orientation across the plane of the bilayer, and a specific lateral localization on the cell surface. These properties will be a test of the physiologic nature of M13 coat protein synthesis and insertion into membrane in a cell-free system.